1. Field of the Invention
The present invention relates to a bearing structure and a spindle motor having the same.
2. Description of Related Art
Generally, a spindle motor includes a rotating shaft that is rotatably supported by a bearing disposed in a bearing housing, a rotator, which is coupled to the rotating shaft, including a magnet, a stator having a coil providing a magnet field to the magnet of the rotator, and a base plate combined with the bearing housing.
Generally, the bearing is press-fitted into the bearing housing, and in a case the bearing is press-fitted into the bearing housing, a large compression stress is applied to the bearing so that a bearing is contracted by the compression stress. Thus a size of the bearing that is press-fitted into the bearing housing is smaller than that of an initial bearing that is not press-fitted into the bearing housing.
Especially, an inner diameter of the bearing press-fitted into the bearing housing is smaller than that of the initial bearing by the compression stress generated while the bearing is press-fitted into the bearing housing. After the bearing is press-fitted into the bearing housing, a gap formed between a circumferential face of the rotating shaft inserted into the bearing and an inner face of the bearing is narrowed whereby a rotating characteristic of the spindle motor is greatly reduced.
In order to prevent decreased rotating characteristic of the spindle motor, the inner diameter of the bearing is expanded by using a resizing process to adjust the gap formed between the rotating shaft and the bearing, after the bearing is press-fitted into the bearing housing,
However, in a case the inner diameter is expanded by the resizing process after the bearing is press-fitted into the bearing housing, a time and a number of processes for manufacturing the spindle motor are increased. Also, even if the inner diameter is expanded by the resizing process, the gap formed between the rotating shaft and the bearing housing may be incorrect.